<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>

        // es6 hash表
        const mapping = new Map();
        // 增
        mapping.set('a', 1);
        mapping.set(true, false);
        mapping.set(false, false);
        const arr = [];
        mapping.set(arr, 2);

        // 删 
        mapping.delete('a');

        // 改
        mapping.set('a', 2);

        // 查
        console.log(mapping.get(false, false));
        console.log(mapping.get(arr));

        console.log(mapping.constructor);
    </script>
</body>
</html>